The Mercedes-Benz W221 is a large luxurysedan built by Mercedes-Benz and is the largest of the saloon/sedan range under the Mercedes-Benz marque. It serves as the current model S-Class. Introduced at the IAA autoshow in Frankfurt in 2005, the W221 is the successor to the previous W220 S-Class. The W221 is slightly larger in all dimensions than the W220, with a longer wheelbase and more interior room. The W221 also features new interior and exterior styling and a number of technologies and features to improve safety, handling, and comfort.

Styling

The W221 S-Class' exterior styling is distinctly different to the W220. The rear styling is similar to the E65BMW 7 Series, and also the Mercedes-BenzMaybach - the larger saloon from Daimler AG's flagship brand, which was released the same year as the E65 BMW 7 Series.

Inside, the W221's interior is also significantly different from the preceding model. The interior features an instrument cluster shroud that also contains the navigation screen, with silver effect air vents below, and a square, analog clock within the vents. Below the vents are metal tab switches with a black field behind them, to control the HVAC system. On the center console, a silver effect control wheel for the COMAND system sits above a piece of wood, surrounded by metal buttons. Throughout the interior, many buttons are metal, with black fields above them denoting the switches' function.

Models

As of 2008[update], the announced production W221 S-Class vehicles feature the following models and engine types (with all internal combustion engines being of 4-valve design):

Alternative propulsion

Features

Safety

The W221 S-Class continues its tradition of leadership in automotive safety. It contains a number of features designed to improve safety for the driver and passengers. Many of the features are evolutions of previous Mercedes developments, such as Brake Assist and Pre-Safe:

Brake Assist Plus - an optional system designed to apportion brake pressure based on pedal speed and distance between the car and objects. This is an evolution of the Brake Assist system found on earlier models, and uses the vehicle's radar, in addition to the usual Brake Assist's monitoring of pedal depression speed, to apply power brake boost as required. This requires the optional adaptive cruise control's radar, so in vehicles not equipped with the latter, standard Brake Assist is substituted.

Pre-Safe - a development of the previous Pre-Safe system fitted to the W220 S-Class, which uses vehicle-dynamic sensors to predict collisions, the W221's system also takes into account closing speed, as measured by the vehicle's radar. If a collision appears likely, Pre-Safe closes all windows and the sunroof, moves all passenger's seats and their head restraints to a safer position, and tightens the seatbelts.

Electronic Stability Program (ESP) - similar to the systems fitted to other Mercedes vehicles, this system measures driver inputs and compares these to the vehicle's path. If these diverge, ESP brakes single wheels selectively to eliminate oversteer (fishtailing) and understeer (plowing), and reduces engine power, if necessary.

Night View Assist - optional, uses two near-infrared (NIR) illuminators mounted in the headlamp clusters and a sensor in the windshield. The infrared beams are picked up by the sensor and an image is displayed in the instrument cluster. Mercedes-Benz claims that this system provides the same viewable distance as high-beam headlights, without blinding oncoming motorists.

Comfort and convenience

The W221 S-Class features a variety of technologies intended to reduce the driver's workload and make the ride smoother and more comfortable for passengers. Like the safety features, many of these items are evolutions of those fitted to earlier models:

Airmatic DC - air suspension, similar to the system fitted to the W211 E-Class, uses air springs and adaptive electronic control to sense road and driving conditions and produce a firm or soft ride. The air suspension is only available for the smaller engines up to S 500. The S 600 and S 65 AMG are equipped with an active suspension system called Active Body Control, which is based on steel springs.

Distronic Plus - optional, a development of the Distronic system fitted to earlier models. Uses more radar systems (long- and short-wave) and improved control logic to detect vehicles ahead and adjust the vehicle's speed to maintain a driver-set distance behind the car in front. The system has more authority over the vehicle than previous Distronic iterations, and can bring the vehicle to a complete stop if necessary, unlike the previous versions.

Drive-Dynamic seats with massage - optional, an evolution of the system fitted to many other Mercedes models, uses air bladders in the seat bolsters to support the driver during cornering. Also, other air bladders provide a four-mode massage function to front-seat passengers.

Heated and Active-Ventilated seats, with heating elements for warming the seats and small fans to keep the seats cool and draw perspiration away from occupants.

Entertainment and other features

Revised COMAND navigation and radio control system, uses the dash-top display and a central knob to navigate menu choices and options. Most frequently-used functions (such as volume) can be controlled by dedicated switches.

Fiber-optic ambient lighting for the dashboard, footwells, and other areas.

Tele Aid, uses GPS tracking and cell phone service to provide assistance. Can be used for information, to call for roadside assistance, or to call for help in emergencies. Automatically calls for help if an air bag or seatbelt tensioner deploys.

Drivetrain technologies

7G-Tronic, Mercedes' 7-speed automatic transmission with two reverse gears, adaptive electronic control, switchable comfort and sport modes, and Touch Shift partial manual control. The transmission is controlled by a small stalk mounted on the steering column, rather than by the usual console-mounted lever. 7G-TRONIC is standard on all S-Class models except the S600 and S65 AMG, where a 5-speed automatic is used instead, as the 7G-TRONIC transmission cannot handle the torque these models produce.

World's First lithium ionhybrid drive system in the S400 BlueHYBRID. Using the same 3.5 liter engine found in the S350, the S400 uses an additional lithium ion battery to drive the car wheels at lower speeds.

Special variants

Mercedes-Benz's high-performance firm, AMG, produces two variants of the W221 S-Class. One of the variants is the S65 AMG, which features restyled front and rear bumpers and rocker panels, larger wheels, brakes, and tires, four exhaust pipes, modified and reprogrammed suspension for sport biased handling, and various interior changes. The S65 also features the M275 6.0 liter, biturbo V12 engine, which is an AMG-modified version of the V12 fitted to the S600 and Maybach. In the S65, the engine produces 612 hp (622 PS/450 kW) and 730 pound-feet (1000 Nm) of torque. The transmission is a heavily reinforced 5-speed automatic.

The second AMG model is the S63 AMG. This variant includes similar modifications as the S65 AMG, but will use AMG's current naturally aspirated M156 6.2 liter V8 engine, which develops 525 bhp (391 kW) and 465 pound-feet (630 Nm) of torque. The engine will power the S63 through the 7G-TRONIC 7-speed transmission, with AMG-programmed electronic control.

Other special variants of this model include those used by government officials in many countries. For example both the President of Ireland and the Taoiseach (Prime Minister) are driven in these types of vehicles. The President's State car is adapted with flag carriers on each front fender.

There are also Guard versions of this car, which are designed to survive attacks by gunfire and RPG's.

Concepts

Mercedes-Benz also built a S 300 BLUETEC HYBRID, which was powered by 2.2L 4-cylinder diesel engine with electric motor. It develops a combined system output of 165 kW / 224 hp and a maximum torque of 560 Nm, with fuel consumption of 5.4 litres of diesel per 100 kilometres. The car was first unveiled in Frankfurt Auto Show[3].

The car was estimated to go on sale in Europe in 2010, and would cost $80000[4].

Mercedes-Benz Ocean Drive

On December 20, 2006, Mercedes unveiled pictures of the Ocean Drive concept slated for debut at the Detroit Motor Show on January 2007. Based on the V12-powered, long-wheelbase S 600 sedan, the car is built on a roofless W221 S-Class. The vehicle features an oversized grille, redesigned LED headlights and restyled trunk/LED taillamp design, a revised air dam, restyled flanks without the wheelhouse bulges, door handles that fit flush into the bodywork and Mercedes-Benz neck-warming technology called AIRSCARF. The car also contains pillarless windows that provide an unobstructed view for occupants when the large soft top is down.